Tunnel kiln car and refractory slab therefor



Fb. 23, 1932. R. w. ROWLAND ,614

TUNNEL KILN CAR AND REFRACTORY SLAB THEREFOR V Fi ledJune 12, 1931 INVENTOR. RoezRl t/ Rama AND BY Y W a /ATTORNEY Patented Feb. 23, 1932UNITED" STATES PATENT OFFICE ROGER W. ROWLAND, OF NEW CASTLE,PENNSYLVANIA, ASSIGNOR TO NEWCASTLE RE- FRACTORIES COMPANY, OF NEWCASTLE, DELAWARE, CORPORATION OF DELA- WARE TUNNEL KILN CAR ANDREFRACTORY SLAB THEREFOR Application filed. June 12,

to withstand high temperatures and to possess considerable mechanicalstrength. Heretofore the superstructure platforms have been composed bya plurality of flat refrac tory slabs of general rectangular contourlongitudinally and transversely and with adjacent slabs arranged end-toend or sideby-side and the supporting posts positioned at the cornersthereof. The slabs and posts are usually made of fire clay or otherhighly siliceous material.

When cars of the above type are loaded with goods to be treated andpassed through a tunnel kiln of standard design, the superstructure andgoods are usually progressively heated to a high temperature and thencooled. Duringthe passage of the car through the heating section orsections of the kiln, the material forming and adjacent to the exposedsurface portions of the slabs will receive more heat than the materialin the center portions thereof. The resulting difference in the rates ofexpansion of these portions of the slabs causes the latter to besubjected to internal stresses, which, when coupled with heavy loadstresses, frequently results in'cracking or a rupture of the'slab and inmany cases breakage of the goods supported thereon. During the passageof the car'through the cooling section of the kiln, the material formingand adjacent to the exposed surface portions of the slabs gives up heatat a greater rate than the material'in the center portions thereof witha resulting difference in the rates of contraction of these portions.Contraction stresses consequently occur, which also tend towards arupture of the slab structure.

The main object of my present invention is the provision of a kiln carplatform slab which is light in weight, low in cost, and in which allportions of the slab structure will 1931. Serial No. 543,823.

be subjected in use to substantially uniform heating and coolingeffects.

In carrying out my invention I form each kiln carplatform'slab with oneor more internal passages extending throughout the slab. When more thanone passage is formed in each slab, all of the passages, may extend inthe same direction, or one or more may be arranged normal to theremaining. In assembling the slabs, I preferably arrange them on the carso that the slab passages will all extend in the same direction as thegeneral path of the kiln chamber atmosphere, whereby the amount of thekiln chamber gases passing through the slab passages will be increased.The amount of material in the slabs is thus reduced as well as the costof production and the weight thereof. Any reduction in weight of thesuperstructure elements will facilitatetheir handling and also decreasethe amount of fuel consumed in fielating these non-productive parts inthe The various features 7 of novelty which characterize myinvention arepointed out with particularity in the claims annexed to and forming apart of this specification. For a better understanding of the invention,however, and the advantages possessed by it reference should be had tothe accompanying drawings and descriptive matter in which I haveillustrated and described pre ferred embodiments of the invention.

Of the drawings:

Fig. 1 is an end elevation of a kiln car having a goods supportingsuperstructure embodying my invention;

Fig. 2 is aside elevation of the car shown in Fig. 1; and

Fig. 3 is a perspective view of a modified slab construction.

In the drawings, I have illustrated a car especially suitable for use inmoving ceramic goods through a tunnel kiln of the mufie type in thedirection indicated. The car as shown, comprises a body portion A whichis formed in the usual manner by superposed rows of refractory blocks Aarranged on a metallic frame A which is provided at its underside withwheels A for engaging tracks 13 arranged in the bottom of the kilnchamber. A series of longitudinally spaced transversely extendingrefractory girders C are arranged on the upper row of blocks A andprovide transverse circulation chambers C through the car. The girders Cserve as supports for the goods carrying superstructure of the car.

The car superstructure as shown consists of a lower platform D, anintermediate platform D and an upper platform D all of which are formedby a plurality of fiat refractory slabs D as hereinafter described andare used for supportin ceramic goods requiring treatment, as indicatedin Fig. 1. The slabs D assembled to form the various platforms arepreferably made of rectangular longitudinal and transversecross-section. The assembled slabs are positioned with their verticaledge portions substantially in contact. The adjacent transverselyextending edge portions of each pair of adjacent slabs in the platform Dare preferably mounted on corresponding girders C. The slabs forn'r ingthe intermediate and upper platforms D and D respectively, are mountedon the lower platform D by posts E positioned at various spaced pointsthereon, preferably at the corners of the slabs.

l/Vhen the car illustrated is employed in a downdraft mullle kiln, forexample, the portions of the slabs of each platform along thelongitudinal center line of the car are usually cut away or recessed topermit a downflow circulation through the car and into the transversechannels C, as indicated by the arrows in Fig. 1. In kilns of this type,the kiln chamber atmosphere is circulated through the channels G intocontact with the walls of combustion chambers (not shown) extendinglongitudinally at the sides of the kiln chamber.

When in use in a downdraft mufl'le kiln, the upper portion of the carsuperstructure is usually heated to a slightly higher temperature thanthe lower central portion thereof. lVhen the platform slabs are madesolid, as has been heretofore the case, the material forming andadjacent to the exposed surfaces of the slabs will receive a greateramount of heat than the material nearer to the centers of the slabs,while the car is passed through the heating sections of the kiln. Acorresponding difference in the rates of expansion of these portions ofeach slab consequently occurs and invariably causes stresses to be setup in the slab which, if sufiiciently great, will cause a rupture in theslab structure. lVith solid slabs arranged as described, these stressesare greatest in the portion of the slabs on which the goods arepositioned. The presence of heavy loads coupled with expansion strainsusually results in the forn'iation of cracks in the slab structure andnot infrequently in a rupture of the slab while in the kiln, damage togoods on the car, and possibly interference with the car movements.During the passage of the cars through the cooling section of the kiln,contraction strains will occure in each slab due to the differences inthe rates at which the different portions give off heat, with resultssimilar to those just described. In general, the slabs in the plat formsD, D D increase in the order named in their liability to damage from theabove causes.

In accordance with my present invention, each of the slabs having aliability for rupturing because of differences in the rates of expansionor contraction of different portions thereof is formed with one or morehorizontal passages D which extend through the portion of the slab whichhas heretofore had the lowest rate of expansion or contraction. lVithslabs of the shape illustrated, the pas- D are of considerably greaterwidth than depth and preferably symmetrically ar-- ranged re ative toone of the center lines thereof. \Vhen the slabs are arranged as shownin a kiln in which the circulation of the kiln chamber atmosphere istransverse to the kiln length. the passages D are advantageously formedand/or arranged in the slabs so as to extend transversely of the car andparallel to the channel C. main circulation is longitudinally of thekiln chamber, as in a direct fire kiln, a longitudinal positioning ofthe passage D is preferable. VVhen so arranged in parallel with the pathof flow of the heating gases, a great er amount of the circulating kilnatmosphere will pass through the passages in both the heating andcooling sections of the kiln.

In the slab construction shown 1n Figs. 1

and 2, two passages D are formed in each slab and symmetrically arrangedat opposite sides of the center line and parallel to the transverse sideedges thereof. When two ich slabs are used for the width of the car,their respective passages will be in alignment. In the slab shown inFig. 3, only one passage D is shown extending through the longerhorizontal portion thereof, while two similar passages D aresymmetrically arranged normal to and intersecting the passage D. Theproportioninp" of the slabs depends largely upon the size of the kilncar on which they are to be used, while the arrangement of the slabpassages depends primarily on the operating conditions to which they areto be subjected. The slabs may be so formed by a suitable casting,pressing, ramming or extruding operation and thereafter fired.

lVhen in use, the slab passages will generally have a circulationtherethrough sulficient in amount to cause the material in the portionsof the slab surrounding the passages to be always subjected tosubstantially the same temperature conditions as the ma terial formingand adjacent to the exposed When the surfaces thereof. All portions ofthe slabs will then have substantially the same rates of expansion andcontraction with a consequent elimination of internal strains in theslab structure.

lhe described slab formation is also advantageous in reducing the amountof ma terial used in making the slabs with a consequent reduction in thecost of production and weight of the slabs. Any decrease in slab weightadvantageously increases the ratio of the weight of goods being treatedto the weight of the unproductive superstructure elements and therebylowers the amount of fuel consumed in heat-ing these elements. Thedecrease in weight also facilitates the handling of the slabs when suchoperations are necessary in loading or unloading the goods.

Vlhile in accordance with the provisions of the statutes, I haveillustrated and described the best forms of embodiment of my inventionnow known to me, it will be apparent to those skilled in the art thatchanges may be made in the forms of the constructions disclosed withoutdeparting from the spirit of my invention as set forth in the appendedclaims and that in some cases only the slabs in the upper platform needbe made in the manner described.

Having now described my invention, wha I claim as new and desireto'secure by Letters Patent, is: I

1. A kiln car having a goods supporting superstructure comprising aplurality of vertically spaced goods supporting platforms, each formedby a horizontally arranged goods supporting refractory slab structure,one of said slab structures having a horizontal passage extendingtherethrough and arranged parallel to the direction of circulation ofthe kiln chamber atmosphere.

2. A kiln car having a goods supporting superstructure comprising aplurality of vertically spaced goods supporting platforms, each formedby a plurality of horizontally arranged goods supporting refractoryslabs of oblong cross-section supported on posts, some of said slabshaving one or more shallow horizontal passages of substantial widthopening to opposite sides thereof and arranged for the passagetherethrough of the kiln chamber atmosphere.

3. A mufiie kiln car having a goods supporting superstructure comprisinga plurality of vertically spaced goods supporting platforms, each formedby a plurality of horizontally arranged flat goods supporting refractoryslabs, said platform slabs having horizontal passages extendingtransversely of said car to permit the circulation therethrough of thekilnchamber atmosphere.

4. A kiln car goods supporting platform slab of rectangularcross-section and formed of refractory material, and having a hori- 63Akiln car goods supporting platformslab or rectangular form and made ofrefractory material, and having a plurality of horizontal passagesformed therein and opening at opposite edge portions thereof, two ofsaid passages being arranged normal to one another and intersecting.

Signed at New Castle, in the count-y of Lawrence and State ofPennsylvania, this 2nd day of June, A. D. 1931.

i V ROGER W. ROVLAND.

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